Is determinism completely rejected in the standard Quantum Mechanics? (1) (2) (3) Jafar Bahreini , Habibollah Razmi , and Mahdi Monfared (1), (3) Department of Philosophy, University of Qom, Qom, I. R. Iran. (2) Department of Physics, University of Qom, Qom, I. R. Iran (1) [email protected] (2) [email protected] (3) [email protected] Abstract Determinism is related to other fundamental concepts such as causality. However, with the growth of quantum physics, determinism became a scientific "dilemma" and has created many challenges in various contemporary sciences. Most of modern physicists chose elimination of determinism. The basic question is: Is determinism completely removable? To answer this question, this paper is to investigate this concept analytically. At first we consider different aspects of the terminology and definition of determinism. Particularly, we pay attention to different kinds of determinism including global/local domain, complete/incomplete form, and the main factor in the formation of events. It is discussed that although determinism took a complete and universal form in classical physics, because of some philosophical ideas, determinism changed into a different concept, even as a problem and an undesirable element, in the standard (Copenhagen interpretation of) quantum mechanics. It is explained that determinism is a complex concept with a number of aspects and characteristics. Prediction, the world accessibility, and connection between the past and the future are the characteristics of the concept of determinism which cannot be set aside from the science. The final result is that, without any pre-assumption or alternative interpretation as what is done in already known realistic and deterministic theories as Bohmian quantum mechanics and/or many worlds interpretation of quantum mechanics, determinism cannot be completely denied in the standard (Copenhagen interpretation of) quantum mechanics. Keywords: Determinism; Prediction; Causality; Quantum Mechanics 1. Introduction It is noteworthy that the concept of determinism is discussed today in many sciences, such as biology, sociology, physics, and ethics (Sarkar, Pfeifer, 2006: 198) and even in theology (Popper, 1991: 5). This concept is related to other fundamental concepts such as causality, prediction, and even notions such as law, free will, intelligence, and chance (Carnap, 1966: 218). The concept of determinism has created many challenges in various contemporary sciences. Although some insist on this idea that determinism is a dead issue, it is a robust doctrine and is quite hard to be killed. Nonetheless, it is fragile in other respects and requires various enabling assumptions to give it a fighting chance (Butterfield, Earman, 2007: 1369). In the classical history of science, most of the natural scientists and materialist philosophers substantiated and developed the concept of determinism (by F. Bacon, Galileo Galilee, Descartes, Newton, Lomonosov, Laplace, Spinoza, and the French 18th-century materialists) (Frolov, 1984: 104). They believed determinism is necessarily mechanistic and abstract (Frolov, 1984: 104). The scholars of that era combined causality and necessity and denied the objective character of chance. So, determinism became unrivaled. But in the twentieth century and in the modern age of physics, the continuity, the causality, the reality and the possibility of representation were denied by most physicists. Both in physics and philosophy, the mechanical age was ended. Determinism was so influential in modern physics; some ones regarded the birth of modern physics as the result of the abandonment of determinism (Jeans, 1943: 125). With the growth of quantum physics, determinism became a scientific dilemma. The physicist's solution was the elimination of determinism (Jeans, 1943: 151). Is determinism really removable? Is there a way to maintain determinism in quantum physics? These are important questions we want to consider in this paper. In our opinion, the root of the problems refers to the conceptual ambiguity of determinism. If we understand the concept of determinism correctly, many misunderstandings (problems) in natural sciences, especially physics, can be removed (solved). As a step towards this, we first consider the terminology of determinism and its definitions. Then, different kinds of determinism with its important characteristics are introduced. Finally, we try to clarify the dilemma of determinism in modern physics. Specifically, we shall show that quantum physics isn’t a completely (globally) indeterministic theory. It is mentionable that all we don't want to consider an alternative approach and/or theory as what already has been considered in some well-known models; but, we want to argue about this fact that if we can have a correct analytical consideration of determinism specially by setting aside some misconceptions about it, even in the standard Copenhagen interpretation of quantum theory won't completely reject determinism. 2. A short review of some definitions of determinism Among a number of other possible definitions of determinism, eight already well-known ones are as in the following: I) William James's definition (simple determinism): " It professes that those parts of the universe already laid down absolutely appoint and decree what the other parts shall be" (Earman, 1986: 5). II) Laplace's determinism (classical determinism): " We ought to regard the present state of the universe as the effect of its antecedent state and as the cause of the state that is to follow. An intelligence knowing all the forces acting in nature at a given instant, as well as the momentary positions of all things in the universe, would be able to comprehend in one single formula the motions of the largest bodies as well as the lightest atoms in the world, provided that its intellect was sufficiently powerful to subject all data to analysis; to it nothing would be uncertain, the future as well as the past would be present to its eyes. The perfection that the human mind has been able to give to astronomy affords but a feeble outline of such an intelligence" (Laplace, 1820: 4). III) Popper's determinism (scientific determinism): Popper introduces a particular type of determinism and calls it 'scientific determinism': " The doctrine of 'scientific determinism' is the doctrine that the state of any closed physical system at any given future instant of time can be predicted, even from within the system, with any specified degree of precision" (Popper, 1991: 36). IV) Causal determinism: Some determinists formulate determinism like this: (a) every event has a sufficient cause; (b) at any given time, given the past, only one future is possible; (c) given knowledge of all former conditions and all laws of nature, an operator could predict at any given time the subsequent history of the universe exactly (Audi, 1999: 228). V) Logical determinism: This doctrine supports the view that future events (i.e. changes in the states of affairs) are determinate, just like what happened in the past, and that statements about them are determinately true or false (Birx, 2009: 299). In other words; if an accident is going to happen, it is true in advance that it will happen (Algra et al., 1999: 519), since it is proven that every statement is true, and if it is not so, it is false. This means that no third truth value other than true or false can be attributed to any statement. If this is the case, then it might be maintained with regard to statements about the future (Borchert, 2006: 5). VI) Epistemic determinism: If it is recognized that an accident will happen, then that accident cannot fail to occur (Algra et al., 1999: 519). This definition is focused on the external realization or non-realization of the event, unlike 'logical determinism' that focuses on what is true or false. VII) Metaphysical determinism: The doctrine which supports that all accidents in this world are steady, invariable, or predetermined. It does not claim that they are known to everybody or predictable by scientific means. Rather, it acknowledges that the future is as little changeable as is the past. Everybody knows what we mean when we say that the past cannot be changed. It is exactly the same sense to say that the future cannot be changed, according to metaphysical determinism (Popper, 1991: 7). In Popper's opinion, " Metaphysical determinism is not clearly testable." (Popper, 1991: 7) However, with the right theology and intellectual reasoning we can understand it. VIII) Theological determinism: This doctrine argues that God determines all things that happened in the past or things that will happen in the present or future, and the cycle of events that he knows will fall out, can fall out. According to some theological theories, the concept of God regards the one who is, among other things, absolutely good, omniscient, and omnipotent and upon whom, moreover, the entire world and everything in it, down to the minutest detail, are absolutely dependent for existence and nature (Borchert, 2006: 8). 3. Classification of determinism into global/local and complete/incomplete kinds In this section, we consider two/four kinds of determinism as in the following: I) Global and local determinism: Determinism can have many instances. If the desired definition includes all instances, we have "global determinism", which refers to the full range. On the other hand, if it includes limited instances, we have "local determinism", which indicates limited cases of a given moment of time. For example, in Laplace's definition, we face a global determinism (Müller, Placek, 2018: 215–252). II) Complete and incomplete determinism: The state of any closed physical system at any given future instant of time can be predicted completely, even from within the system, with any specified degree of precision; as a result, this is "complete determinism". And if the time, prediction, or degree of precision is not complete, we have "incomplete determinism". Therefore, the forecast will be vague or very probabilistic. 4. Classification of determinism based on the main factor in the events formation: Various factors in the past can be considered as determining the future.